How Small Will They Get? - A Look At Super-Mini Amplifiers
Recent models of audio super-mini amplifiers prove that audio technology has gone the same path as computer technology and cell phones. Products are shrinking at a rapid tempo. At the same time, manufacturers are packing in more and more features. You most likely still recall the good old tube amps which would dominate the living room. Whilst tube amps are even now popular among fanatics, audio amplifiers these days are solid-state amps for the most part.
Modern solid-state amplifiers merge the traditional pre amp and power amp stages into a neat single box no larger than a DVD player. Thanks to latest developments in audio technology in terms of amplifier power efficiency, a new generation of super-miniature amps has become feasible, such as the Amphony Model 100 microFidelity amp. These mini amps use no more room than a deck of cards but deliver up to 50 Watts, which is plenty to drive a speaker to high volume.
“Class-A” and “Class-AB” amplifier topologies were the two primary amplifier architectures of historical audio amplifiers. These technologies have relatively low power efficiency. Only a small percentage of the consumed power - typically in the order of 20% to 30% - is actually transformed into audio by analog amplifiers. The remaining portion is radiated as heat. Therefore analog amplifiers require a reasonable amount of cooling. The amount of cooling depends on the amplifier rated output power. These heat sinks prevent the amplifier to be built into a small form factor.
Digital “Class-D” amplifiers offer higher power efficiency than analog amplifiers - normally around 80% to 95% - and thus can be miniaturized. One main disadvantage of “Class-D” amplifiers is the fact that digital “Class-D” amplifiers use a switching stage at the output which causes non-linearity and as a result some amount of distortion of the audio signal. This downside has slowed the progress of digital amplifiers.
More recent “Class-T” and newer “Class-D” amplifier architectures, such as Amphony’s Model 100, incorporate a feedback mechanism where the output of the amplifier is fed back to the input. Using this design, the amplifier is capable to compensate for errors caused by the switching output stage. Amplifiers based on this design are able to accomplish low audio distortion similar to previous analog amplifiers but at the same time the power efficiency of digital amplifiers.
These new generation miniature audio amplifiers are suited for a range of new applications where traditional audio amplifiers have failed. These applications include installations, such as in-ceiling installations, with minimal space or connecting speakers to a cable box or DVD/MP3 player where minimum space is important.